Vascular prosthesis

ABSTRACT

A vascular endoprosthesis ( 1 ) is disclosed which is capable of being arranged internally to the aortic arch (O), comprising: a tubular main body ( 2 ), to be housed in the internal lumen of the aortic arch (O); three tubular secondary bodies ( 3, 4, 5 ), originating from the main body ( 2 ) and to be housed in the right carotid artery (R), in the left carotid artery (L) and in the subclavian artery (S); and stent-type engagement means ( 10, 11, 13, 14, 15 ), intended to hold a longitudinal end portion ( 21, 22, 31, 41, 51 ) of the main and secondary bodies onto the internal wall of the respective vessel (FIG.  5 ).

This application is the U.S. national phase under 35 U.S.C. 371 ofInternational Application No. PCT/IT2006/000527, filed 11 Jul. 2006,which designated the U.S., the entire contents of which is herebyincorporated by reference.

The present invention refers to a vascular endoprosthesis, apt toexclude an aneurysmal portion of the aorta, and in particular of theaortic arch or the thoraco-abdominal aorta.

As is well-known, the aorta is the most important artery supplying bloodto the organism. It originates from the heart as ascending aorta andcontinues at the thoracic level as aortic arch and descending aorta,subsequently extending into the abdomen where it divides, at the levelof the bifurcation, into two iliac arteries. Among the arteriesoriginating from the aorta, some are of fundamental importance: theright common carotid artery, the left common carotid artery and the leftsubclavian artery, all of which initiate from the aortic arch and supplyblood to the cerebral region and to the upper limbs; the intercostalarteries, originating from the descending thoracic aorta to supply thespinal cord; and lastly, the visceral arteries, extending from the upperabdominal section to supply all the abdominal organs.

The aorta has an average diameter of 2 cm. and its wall is made ofelastic fibres (primarily in the thoracic section) and muscular fibres(primarily in the abdominal section). Aneurysms, that is dilations ofthe aorta, are among the most severe pathologies affecting the aorta, inparticular the thoracic and thoraco-abdominal portion.

Conventional surgery for treatment of the aneurysmal aorta-thoracicand/or thoraco-abdominal—calls for a resection of the aorta portioninvolved and its replacement with a prosthesis that is anastomosedbetween the two vascular stumps resulting from the resection. Generally,during this procedure the patient is subjected to hypothermicextracorporeal circulation.

Despite the remarkable advances made in conventional surgery over thepast few years in treating aneurysms of the aortic arch and thethoraco-abdominal aorta, major problems that decisively conditionsurgical results remain unresolved, as conventional surgery is stillburdened by high mortality and morbidity, with a particularly high riskof paraplegia, cerebral ischemia, respiratory and/or renalinsufficiency, etc. The major problems conditioning surgical resultsensue from the lengthy times required for the “aortic cross-clamping” tosuture the prosthesis in situ, and from the use of extracorporealcirculation systems, the latter intended to protect such particularlysensitive organs as the central nervous system, the cardiovascularsystem, renal function, etc.

The advent of endovascular surgery in the surgical panorama of the lastdecade has certainly modified and improved surgical results fortreatment of the aneurysmal pathology, especially of the descendingthoracic aorta, significantly decreasing the incidence of such seriouscomplications as paraplegia. The endovascular approach requires noresection of the aortic portion involved by the aneurysm, but simply theinsertion of an endoprosthesis that reproduces the correct vasculardiameter, thereby excluding the aneurysm and re-establishing a correctblood flow. Said significant improvement is certainly attributable tothe elimination of aortic cross-clamping, the need for extracorporealcirculation and of other organ protection systems requiring lengthy andextensive use of anesthesia.

Regrettably, endovascular surgery, certainly valid for the descendingthoracic aorta, has found no effective application for the aortic archand for the thoraco-abdominal aorta, where attempts have proved whollyunsatisfactory and are limited exclusively to a “hybrid” treatmentcombining a conventional surgical approach and an endovascular approach.

Thus the technical problem presented and solved by the present inventionis to provide a vascular prosthesis capable of overcoming the drawbacksmentioned hereto with reference to the known procedure.

The problem is solved by a vascular endoprosthesis as per claim 1.

Preferred features of the present invention are provided for in thedependent claims thereof.

The present invention provides several relevant advantages. The mainadvantage lies in that the prosthesis of the invention allows for adrastic reduction of the time required for the in situ anastomoses ofthe prosthesis itself and obviates the need for extracorporealcirculation and organ protection systems. Hence, it significantlyreduces surgical and anaesthesia times, leading to optimal treatment ofthe aneurysm pathology of the aortic arch and of the thoraco-abdominalaorta.

Other advantages, features and operation modes of the present inventionwill be elucidated in the following detailed description of some of theembodiments thereof, given by way of example and not wholly exhaustive.Reference will be made to the annexed drawings, wherein:

FIG. 1 shows a schematic front perspective view of an embodiment of thevascular endoprosthesis according to the present invention;

FIG. 2 shows a cross section of the prosthesis of FIG. 1 taken alongline A-A of the latter Figure;

FIG. 2A illustrates some geometric parameters of a component of theprosthesis of FIG. 1;

FIG. 3 shows another cross section of the prosthesis of FIG. 1, takenalong line B-B of the latter Figure;

FIG. 4 shows a perspective view of the endoprosthesis of FIG. 1implanted in correspondence of a section of the aortic arch; and

FIG. 5 shows a partially sectional perspective view of theendoprosthesis of FIG. 1 during its insertion in correspondence with thesection of the related aortic arch, before the opening of the endsequipped with metal supports and with part of the prosthesis stillexternal to the aneurysm.

Initially referring to FIG. 1, a vascular endoprosthesis according to anembodiment of the invention is generally denoted by 1. In the presentexample, the endoprosthesis 1 is conceived to be implanted incorrespondence with the aortic arch, and FIG. 4 shows the endoprosthesis1 in situ.

The endoprosthesis 1 comprises a substantially tubular main body 2intended to be lodged in the internal lumen of the aortic arch, denotedby O in FIG. 4.

Three secondary bodies branch off from main body 2. These are alsotubular and marked 3, 4 and 5, respectively, each of which to beinserted into the internal lumen of a blood vessel originating from theaortic arch. In particular, the first secondary body 3 is intended to beinserted into the right common carotid artery, denoted by R in FIG. 4,the second secondary body 4 into the left common carotid artery, denotedby L, and the third secondary body 5 into the left subclavian artery,denoted by S.

Referring also to the section of FIG. 3, both the main body 2 and thesecondary bodies 3-5 are made of impermeable biocompatible material.Ideally, this material should be elastically deformable and furrowed,(corrugated) e.g. Dacron.

In correspondence with each of the two longitudinal end portions 21 and22 of the main body 2 are respective engagement means, denoted by 10 and11, respectively, to secure end portions 21 and 22 to the internal wallof the corresponding section of the aortic arch. Engagement means 10, 11are shown in greater detail in FIG. 2.

In this example, fixing means 10 and 11 are based on self-expandableelastic elements set onto the internal walls of the blood vessels, in anexpanded configuration. Specifically, each of means 10, 11 consists of ashaped annular weft made of (biocompatible) elastically deformablematerial, externally surrounding and being supported by the respectiveend portions 21, 22 of the main body 2, the latter preferably made ofthe same biocompatible elastically deformable material. Preferably, incorrespondence with said ends 21, 22, the material should not befurrowed. (corrugated)

In the present example said weft is formed by three independent metallicannular elements, denoted by 101, 102 and 103, respectively, for themeans 10, each having a substantially sinusoidal or loop-shaped profile.These annular elements are circumferentially arranged onto the main body2 and longitudinally spaced in correspondence with the respective endportion 21, 22. Preferably, and analogously to stent-type securingsystems already used in existing endoprostheses, the means 10, 11 aremade of a shape retentive material, typically thermally preformedNitinol or an alloy thereof.

The annular elements of 101-103 type are secured on the end portions 21,22 of the main body 2, e.g. by suture.

As shown in FIG. 2A, preferably each annular element 101-103 has a pitchP equal to about 10 mm, a loop width A equal to about 8 mm and a wirediameter d comprised in a range of about 0.1-1.0 mm.

Moreover, the engagement means 10, 11 each preferably involve a distalsection T of the main body 2, of an approximate length comprised between2-3 cm and of diameter, or gauge, D ranging between 26-46 mm.

Each of the secondary bodies 3-5 further comprises, in correspondencewith a respective distal end 31, 41, 51 thereof, respective engagementmeans 13, 14, 15, having an overall configuration analogous to that ofthe above-described means 10, 11.

Of course, the specific dimensions and extension of engagement means13-15 of the secondary bodies 3-5 will be adapted to the configurationof the respective blood vessel of insertion. In particular, for thesecondary bodies 3-5 the pitch P could equal about 2 mm, a wire diameterd equal to about 0.4 mm and a distal section, concerned by means 13-15,of length T equal to about 20 mm and diameter D equal to about 8-14 mm.

Preferably, in correspondence with engagement means 10, 11 and 13-15 thediameter of the respective main 2 and secondary 3-5 bodies (andtherefore that of the related annular elements) is oversized withrespect to that of the respective blood vessel in a percentage equal toabout 10-15% of the diameter of the vessel itself, and this in order toallow for improved securing in situ of the endoprosthesis 1.

The provision of the engagement means only distally to each of thebodies 2-5 allows for improved adaptation to the anatomical site of theendoprosthesis 1 as a whole, leaving the central part of the main body 2and of the secondary bodies 3-5 free for adaptation.

The engagement means 10, 11 and 13-15 assume an initial configuration ofminimal encumbrance, shown in FIG. 5, in which they are compressed orfolded to allow for insertion of the respective body 2-5 into therelated blood vessel, and a second unfolded or extended configuration,shown in FIG. 4, in which they engage the wall of the blood vesselitself, securing the endoprosthesis 1 in situ.

The engagement means 10, 11 and 13-15 can be remotely controlled(maneuvered) to allow transition from the first to the secondconfiguration mentioned hereto. For this purpose, the endoprosthesis 1comprises a fourth tubular body 6 forming a maneuvering channel andarranged in a position substantially centered with respect to the mainbody 2 and, with the endoprosthesis in situ, below the secondary bodies3-5. In the present example, maneuvering channel 6 has a diameter ofabout 10 mm. This maneuvering channel 6 can house one or moremaneuvering elements 7 accessible from the outside, and in particular,as shown in the example in FIG. 5, several maneuvering wires to unfoldeach of the engagement means 10, 11 and 13-15.

Upon implant of the endoprosthesis 1, the procedure described below iscarried out, with reference to the example applicable to the aortic archand the related epiaortic vessels.

First, the aortic segment to be treated is exposed, using a conventionalsurgical approach of codified cuts, such as median sternotomy orbilateral thoracotomy for the aortic arch or thoracophrenolaparotomy forthe thoraco-abdominal aorta.

The portions of blood vessels at which the engagement means 10, 11 and13-15 are to be positioned are non-aneurysmal sections adjacent to theaneurysmal portions. At each of the “healthy” portions, the physician,usually a vascular surgeon, performs a “purse string”, a techniquefamiliar to experts in the field and consisting in a pair ofside-by-side stitches intended to constrict the section of vesselinvolved when pulled.

The example presented is of five “purse string” performed on healthyarterial wall, i.e. at the level of the ascending aorta (incorrespondence with the end portion of the proximal end 21 of theendoprosthesis 1), at the level of the descending thoracic aorta (incorrespondence with the final position of the distal end 22) and at thelevel of the epiaortic vessels (in correspondence with the finalposition of the collateral ends 31, 41 and 51 relating to the rightcommon carotid artery R, the left common carotid artery L and the leftsubclavian artery S, respectively).

After partial heparinization and using the well-known Seldingertechnique, five ends of the endoprosthesis 1 are inserted, containingthe rapid-expansion engagement means 10, 11 and 13-15, which are held inplace by the five previously performed purse strings and held incompressed configuration by the maneuvering wires 7.

Upon positioning the endoprosthesis 1—which is not yet operative—asmentioned above, the five ends 21, 22, 31, 41 and 51 are unfolded, i.e.brought from the compressed configuration to the extended one, in thefollowing sequence:

-   -   I. left subclavian artery-related end 51,    -   II. left carotid artery-related end 41,    -   III. right carotid artery-related end 31,    -   IV. proximal aorta-related end 21,    -   V. distal aorta-related end 22.

With the unfolding of the engagement means 10, 11 and 13-15 anastomesesare executed with the aortic arch O and one of the above mentionedepiaortic vessels R, L and S. Note that the engagement means 10, 11 and13-15 allows for the performance of the anastomoses not though avascular suture, but rather through an endovascular-type release system;thus we may in effect define it as “endoanastomosis”.

The time of execution for the five anastomoses is envisaged to be lessthan two minutes, certainly brief enough as not to create ischemicproblems to the brain.

Of course, each of the maneuvering wires 7 of the channel 6 could beindicated by a suitable identifying element, e.g. an alphanumericcharacter, of the respective maneuvered engagement means 10, 11 and13-15, visible from the outside.

The above-indicated sequence (I)-(V) allows for effective purging of airfrom the epiaortic trunks, preventing the risk of embolizing the brain.

It should be noted that the proposed configuration, in which the fiveends of the maneuvering wires 7 issue from the sole collateral branch ofthe prosthesis 1 not equipped with stents, i.e. from the maneuveringchannel 6, also facilitates control of the endoprosthesis 1 itself andthe purging of air to the outside.

Once the endoprosthesis 1 in place is operating, and after checking thatthe aneurysmal sac is no longer supplied as it is excluded from thecirculation, the aneurysm is opened up.

Note that in the present example, since the collateral branch 3 isinserted directly into the right common carotid artery R, and not intothe brachiocephalic trunk (in order to simplify and unify the gauges ofthe collateral branches) a surgical revascularization of the rightsubclavian artery should be provided for; such a revascularization canbe carried out at leisure at the conclusion of the procedure by usingthe collateral branch 6.

This particular endoprosthesis may also be used for replacement of thethoraco-abdominal aorta, in such case using four secondary bodies to beinserted into the celiac tripod, the superior mesenteric artery, theright renal artery and the left renal artery.

Moreover, in case of need the prosthesis described hereto may also beused in conventional surgery, by resecting the proximal or distal endequipped with a stent (or by removing the endoanastomosis site) andsuturing it to the residual (ascending and/or descending) aortic stump,for highly extensive pathologies, such as acute type A dissections orMarfan syndrome.

Furthermore, it will be appreciated that this invention means that asingle item can fulfill the needs for treatment of the aortic arch andof the thoraco-abdominal aorta, thus simplifying its implementation andmarketing.

Thanks to its simplicity and speed of use, the invention also offers thepotential of expanding the range of operators who can carry out vascularprosthetic fitting surgery, increasing then number of potentialbeneficiaries to include vascular surgery centers currently not able toprovide these types of treatment.

It should be apparent by now that the above-described vascularprosthesis would drastically reduce surgical times from the currentapproximate 120-180 min to the 4-5 min required for preparation of theentire technique.

The invention further refers to a method of treating vascularpathologies that, in its broadest definition envisages:

-   -   providing an endoprosthesis as defined above, and comprising in        particular a substantially tubular main body capable of being        introduced into the internal lumen of a main blood vessel and at        least one secondary body, also basically tubular and originating        from said main body, capable of being introduced into the        internal lumen of a secondary blood vessel branching off the        main vessel;    -   inserting said endoprosthesis into the main and secondary blood        vessels; and    -   setting and securing the endoprosthesis in position.

The present invention has hereto been described with reference topreferred embodiments thereof. It is understood that there might beother embodiments referable to the same inventive principle, all fallingwithin the protective scope of the claims hereinafter.

The invention claimed is:
 1. A vascular endoprosthesis capable of beingset internally to a blood vessel, in particular a portion of aorta,comprising: a substantially tubular main body, to be housed in theinternal lumen of a main blood vessel; at least one secondary body, alsosubstantially tubular, and originating from and fixed to said main body,to be housed in the internal lumen of a blood vessel branching off themain vessel; engagement means, associated with and fixed to each of saidmain body and secondary body and arranged in correspondence with atleast one respective longitudinal end portion of each, apt to hold saidend portions onto the internal wall of the respective blood vessel; anda maneuvering channel originating from said main body and, wherein themaneuvering channel is configured for remotely controlling theconfiguration of said engagement means; wherein said vascularendoprosthesis is pre-assembled prior to being implanted in situ.
 2. Theendoprosthesis according to claim 1, wherein said engagement means areapt to assume a first configuration of minimal encumbrance, allowing forinsertion of the respective main or secondary body into the relatedblood vessel, and a second unfolded configuration, engaging the wall ofthe blood vessel, securing in position the respective longitudinal endof said main or secondary body.
 3. The endoprosthesis according to claim2, wherein said engagement means are apt to be circumferentiallycompressed to assume said configuration of minimal encumbrance.
 4. Theendoprosthesis according to claim 1, wherein said engagement means areself-expandable.
 5. The endoprosthesis according to claim 1, whereinsaid engagement means are arranged onto the external wall of therespective main or secondary body.
 6. The endoprosthesis according toclaim 1, wherein said engagement means comprise one or more elasticallydeformable elements.
 7. The endoprosthesis according to claim 6, whereinsaid or each of said elastically deformable element or elementscomprises an annular element circumferentially arranged onto therespective main or secondary body.
 8. The endoprosthesis according toclaim 6, wherein said or each of said elastically deformable elementscomprises a loop-shaped element.
 9. The endoprosthesis according toclaim 6, wherein said engagement means comprise several elasticallydeformable elements arranged longitudinally side-by-side along therespective main or secondary body.
 10. The endoprosthesis according toclaim 1, wherein said engagement means comprise one or more stent-typeelements.
 11. The endoprosthesis according to claim 1, wherein saidengagement means comprise one or more shape memory-type elements. 12.The endoprosthesis claim 1, comprising maneuvering means that can beoperated from the outside for remote control of the configuration ofsaid engagement means.
 13. The endoprosthesis according to claim 12,wherein said maneuvering means comprise one or more maneuvering wires.14. The endoprosthesis according to claim 12, wherein said maneuveringmeans bear identifying elements of the respective engagement means. 15.The endoprosthesis according to claim 1, wherein said main body is aptto be housed in a portion of aorta.
 16. The endoprosthesis according toclaim 15, wherein said main body is apt to be housed in thethoraco-abdominal aorta.
 17. The endoprosthesis according to claim 15,wherein said main body is apt to be housed in the aortic arch.
 18. Theendoprosthesis according to claim 17, comprising a secondary body apt tobe housed in the right carotid artery.
 19. The endoprosthesis accordingto claim 17, comprising a secondary body apt to be housed in the leftcarotid artery.
 20. The endoprosthesis according to claim 17, comprisinga secondary body apt to be housed in the left subclavian artery.
 21. Theendoprosthesis according to claim 1, wherein said main body and/or saidsecondary body or bodies are made of an elastically deformable material.22. The endoprosthesis according to claim 1, wherein said main bodyand/or said secondary body or bodies are at least partially made of afurrowed (corrugated) material.
 23. The endoprosthesis according toclaim 1, wherein, in correspondence of said engagement means, thediameter of the respective main and/or secondary body is oversized withrespect to that of the respective blood vessel of insertion.
 24. Theendoprosthesis according to claim 23, wherein said oversizing iscomprised in a range of about 10-15%.
 25. A method of treating vascularpathologies, comprising the following steps: (a) providing anendoprosthesis of claim 1, comprising a substantially tubular main bodyto be housed in the internal lumen of a main blood vessel and at leastone secondary body, also substantially tubular and originating from saidmain body, apt to be housed in the internal lumen of a secondary bloodvessel branching off the main vessel; (b) inserting said endoprosthesisinto said main and secondary blood vessels; and (c) securing saidendoprosthesis in position.
 26. The method according to claim 25, whichis a method of treating aneurysmal blood vessels.
 27. The methodaccording to claim 25, wherein said main blood vessel is the aorta. 28.The method according to claim 27, wherein said step (b) provides for theinsertion of the main body of the endoprosthesis into the aortic arch.29. The method according to claim 28, wherein said step (b) provides forthe insertion of the secondary body or bodies of the endoprosthesis intoone or more blood vessels selected from a group comprising the rightcarotid artery, left carotid artery and left subclavian artery.
 30. Themethod according to claim 29, wherein said step (c) provides for theclamping of the endoprosthesis in situ by activating related holdingmeans according to the sequence: (I) left subclavian artery; (II) leftcarotid artery; (III) right carotid artery; (IV) proximal aorta; (V)distal aorta.
 31. The method according to claim 27, wherein said step(b) provides for the insertion of the main body of the endoprosthesisinto the thoraco-abdominal aorta.
 32. The method according to claim 25,wherein said step (b) provides for the temporary setting and securing insitu of the endoprosthesis by temporary restriction of the internalvascular lumen of healthy vascular portions.
 33. The method according toclaim 32, wherein said temporary restriction of the internal lumen ofhealthy vascular portions is obtained by performing “purse string” incorrespondence with said portions.
 34. The method according to claim 25,providing for removal of a vascular portion external to theendoprosthesis, performed in a surgical procedure temporally separatefrom that of insertion of the endoprosthesis itself.
 35. The methodaccording to claim 25, wherein said step (a) provides for the use of anendoprosthesis capable of being set internally to a blood vessel, inparticular a portion of aorta, comprising: a substantially tubular mainbody, to be housed in the internal lumen of a main blood vessel; atleast one secondary body, also substantially tubular, and originatingfrom and fixed to said main body, to be housed in the internal lumen ofa blood vessel branching off the main vessel; engagement means,associated with and fixed to each of said main body and secondary bodyand arranged in correspondence with at least one respective longitudinalend portion of each, apt to hold said end portions onto the internalwall of the respective blood vessel; and a maneuvering channeloriginating from said main body and, wherein the maneuvering channel isconfigured for remotely controlling the configuration of said engagementmeans; wherein said vascular endoprosthesis is pre-assembled prior tobeing implanted in situ.
 36. A vascular endoprosthesis capable of beingset internally to a blood vessel, in particular a portion of aorta,comprising: a substantially tubular main body, to be housed in theinternal lumen of a main blood vessel; a plurality of secondary bodies,which are substantially tubular and fixed to said main body, to behoused in the internal lumen of a blood vessel branching off the mainvessel; engagement means, which is fixed to each of said main body andsecondary body, arranged in correspondence with at least one respectivelongitudinal end portion of each, apt to hold said end portions onto theinternal wall of the respective blood vessel; and a maneuvering channeloriginating from said main body and, wherein the maneuvering channel isconfigured for remotely controlling the configuration of said engagementmeans; wherein said main body and said secondary bodies are made as asingle body, and said vascular endoprosthesis is pre-assembled prior tobeing implanted in situ.